Porous structures produced by additive layer manufacturing

ABSTRACT

A three-dimensional structure is formed when layers of a material are deposited onto a substrate and scanned with a high energy beam to at least partially melt each layer of the material. Upon scanning the layers at predetermined locations at least a first segment overlapping a second segment and underlapping a third segment is formed.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 14/969,695, filed Dec. 15, 2015, the disclosure of which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to preparing porous structures,and in particular to the preparation of mesh structures by way ofadditive manufacturing.

BACKGROUND OF THE INVENTION

The field of free-form fabrication has seen many important recentadvances in the fabrication of articles directly from computercontrolled databases. These advances, many of which are in the field ofrapid manufacturing of articles such as prototype parts and mold dies,have greatly reduced the time and expense required to fabricatearticles. This is in contrast to conventional machining processes inwhich a block of material, such as a metal, is machined according toengineering drawings.

Examples of modern rapid manufacturing technologies include additivelayer manufacturing techniques such as electron beam melting, selectivelaser sintering (SLS), selective laser melting (SLM), and otherthree-dimensional (3-D) processes. When employing these technologies,articles are produced in layer-wise fashion from a laser-fusible powderthat is dispensed one layer at a time. The powder is sintered in thecase of SLS technology and melted in the case of SLM technology, by theapplication of laser energy that is directed in raster-scan fashion toportions of the powder layer corresponding to a cross section of thearticle. After the sintering or melting of the powder on one particularlayer, an additional layer of powder is dispensed, and the processrepeated, with sintering or melting taking place between the currentlayer and the previously laid layers until the article is complete.Detailed descriptions of the SLS technology may be found in U.S. Pat.Nos. 4,863,538, 5,017,753, 5,076,869, and 4,944,817, the entiredisclosures of which are incorporated by reference herein. Similarly, adetailed description of the use of SLM technology may be found in U.S.Pat. No. 7,537,664 (“the '664 Patent”), the disclosure of which isincorporated by reference herein. The SLM and SLS technologies haveenabled the direct manufacture of solid or porous three-dimensionalarticles of high resolution and dimensional accuracy from a variety ofmaterials including wax, metal and metal alloys, metal powders withbinders, polycarbonate, nylon, other plastics and composite materials,such as polymer-coated metals and ceramics.

Other non-powder based additive manufacturing technologies are alsoknown to produce high resolution and dimensionally accurate articles.For example, in fused filament fabrication (FFF) or Plastic Jet Printing(PJP), strands of molten material are extruded from a nozzle to formlayers onto a substrate in which the material hardens upon extrusion.Using digital light processing (DLP), photosensitive resin plastic iscured by light and built layer by layer from the bottom-up or a vat ofliquid polymer is exposed to balanced levels of ultraviolet light andoxygen to produce a part often from the top-down. In inkjet 3D printing,a liquid binding material is selectively deposited across a thin layerof a powder and the process is repeated in which each new layer isadhered to the previous layer.

The invention claimed in the '664 Patent is one of several commonlyowned by Howmedica Osteonics Corporation that relate to the additivemanufacturing area. For instance, U.S. Pat. Appl. Publ. Nos.2006/0147332 A1 (“the '332 Publication”) U.S. Pat. Appl. Publ. No.2011/0014081 A1 (“the '081 Publication”), U.S. Pat. No. 8,992,703 (“the'703 Patent”), U.S. Pat. No. 9,135,374 (“the '374 Patent”), and U.S.Pat. No. 9,180,010 (“the '010 Patent”), the entire disclosures of whichare hereby incorporated by reference herein, have taught the generationand organization of a population of porous geometry, a mathematicalrepresentation of the portion of geometry of the porous structure to bebuilt within a region defined by a predetermined unit cell or imaginaryvolume, to fill and form a predetermined build geometry, i.e., a modelbuild structure, which may be used to produce a near net-shape of anintended porous tissue in-growth structure. The predetermined buildgeometry, or overall computer-aided design (CAD) geometry, may refer tothe mathematical or pictorial representation (such as that on a computerdisplay) of the intended physical structure to be manufactured. In thecase of physical components that include both porous material and solidmaterial, the predetermined build geometry may be an assembly of solidand porous CAD volumes that define the outer boundaries of therespective solid and porous materials intended to be manufactured.Furthermore, these applications teach the randomization of the positionof interconnected nodes, or points of intersection between two struts orbetween a strut and a substrate, that define each of the porousgeometries while maintaining the interconnectivity between the nodes. Asfurther taught in these applications, such randomization may beaccomplished by changing the coordinate positions of the nodes, in thex, y, and z directions of a Cartesian coordinate system, to newpositions based on a defined mathematical function.

During surgical operations on one or more bones, orthopedic implants aregenerally adhered to a bony surface by bone cement. Even properpreparation of delivery of bone cement to a smooth bony surface canresult in aseptic loosening of the implant and cement over time,especially when filling large void spaces such as in the proximal tibiaand distal femur, requiring a revision surgery to be performed. Currentimplants, which typically require the use of biocompatible materialssuch as titanium, used to retain bone cement lack flexibility and aredifficult to shape for a proper fit in a non-uniform space. Suchimplants are non-porous and thus lack limited surface area for contactwith bone. Implants produced using additive layer manufacturingtechniques have been built with strong scaffolds, but such implants aretoo rigid to allow for adequate deformation to fill void spaces createdby bone degradation.

Thus, a new method is needed to create flexible structures which stillprovide mechanical strength to resist tensile and compressive forces,especially impact forces applied to bone and orthopedic implants.

BRIEF SUMMARY OF THE INVENTION

In accordance with an aspect, a three-dimensional structure may beformed. In forming the three-dimensional structure, a first layer of amaterial may be deposited onto a substrate. A first layer of thematerial may be scanned with a high energy beam to at least partiallymelt the first layer of the material. Successive layers of the materialmay be deposited onto the first layer. Each of the successive layers ofthe material may be scanned with the high energy beam at predeterminedlocations to form at least a first segment overlapping a second segmentand underlapping a third segment.

In some arrangements, any of the segments may be a curvilinear segment.In some arrangements, any of the segments may be a rectilinear segment.In some arrangements, any of the segments may include both curvilinearand rectilinear portions.

In some arrangements, the three-dimensional structure may be in the formof a mesh defined by a weave pattern or a chain-link pattern.

In some arrangements, the material may be any of titanium, a titaniumalloy, stainless steel, magnesium, a magnesium alloy, cobalt, a cobaltalloy, a cobalt chrome alloy, nickel, a nickel alloy, tantalum, andniobium, polyethylene (PE) and variations thereof, polyetheretherketone(PEEK), polyetherketone (PEK), acrylonitrile butadiene styrene (ABS),silicone, and cross-linked polymers, bioabsorbable glass, ceramics, andbiological active materials including collagen/cell matrices.

In some arrangements, when scanning each of the successive layers atpredetermined locations a fourth segment spaced from the first segment,underlapping the second segment, and overlapping the third segment maybe formed.

In some arrangements, the second and third segments may be spaced fromeach other.

In some arrangements, the third segment may be the second segment suchthat the first segment underlaps and overlaps the second segment. Insuch arrangements, the second and third segments may form part of alink, which may form a portion of a chain mail structure.

In some arrangements, the first segment may completely surround thesecond segment. In such arrangements, the first segment may be a link ofa chain mail structure.

In some arrangements, the second segment may completely surround thefirst segment. In such arrangements, the second segment may be a link ofa chain mail structure.

In some arrangements, when scanning each of the successive layers atpredetermined locations a plurality of segments may be formed that maycompletely surround the first segment.

In some arrangements, a first additional layer of the material may bedeposited onto at least a predetermined location of the first segment.In some such arrangements, the first additional layer of the materialmay be scanned with the high energy beam at the predetermined locationof the first segment. In this manner, the first additional layer of thematerial may be fused to the first segment at the predeterminedlocation.

In some arrangements, successive additional layers of the material maybe deposited onto the first additional layer. In some such arrangements,each of the successive additional layers may be scanned with the highenergy beam at predetermined locations. In this manner, at least a firstadditional segment may be formed overlapping a second additional segmentand underlapping a third additional segment in which the firstadditional segment may be fused to at least the first segment at thepredetermined location of the first segment.

In some arrangements, the third additional segment may be the secondadditional segment such that the first additional segment underlaps andoverlaps the second additional segment. In such arrangements, the secondand third segments may form part of a link, which may form a portion ofa chain mail structure.

In some arrangements, when scanning each of the successive additionallayers at predetermined locations, a fourth additional segment spacedfrom the first additional segment, underlapping the second additionalsegment, and overlapping the third additional segment may be formed.

In some arrangements, when depositing the first additional layer of thematerial, the first additional layer of the material may be furtherdeposited onto predetermined locations of the second, third, and fourthsegments. In some such arrangements, when scanning the first additionallayer of the material with the high energy beam, the first additionallayer may be fused to each of the second, third, and fourth segments atthe respective predetermined locations of the second, third, and fourthsegments.

In some arrangements, successive additional layers of the material maybe deposited onto the first additional layer. In some such arrangementsin which successive additional layers of the material may be depositedonto the first additional layer, each of the successive additionallayers may be scanned with the high energy beam at predeterminedlocations to form at least one symbol. In some such arrangements formingat least one symbol, any of such symbols may be fused to at least thefirst segment at the predetermined location of the first segment. Insome such arrangements forming at least one symbol, any of such symbolsmay be an alphanumeric character.

In some arrangements, when scanning each of the successive layers atpredetermined locations, at least one barb may be formed. Any such barbsmay extend from any of the first, second, and third segments.

In some arrangements, when scanning each of the successive layers atpredetermined locations, a first series of segments extending in a firstdirection and a second series of segments extending in a seconddirection transverse to the first direction may be formed. The firstseries of segments may include the first segment. The second series ofsegments may include the second and third segments. Some or all of thesegments of the first series of segments may overlap a plurality ofsegments of the second series of segments and may underlap anotherplurality of segments of the second series of segments such that thefirst and second series of segments form a first mesh.

In some arrangements, the first mesh may be a flexible sheet. The firstmesh may be foldable such that a substantially planar first portion ofthe first mesh lies in a plane at an angle of up to substantially 180degrees to a plane in which a substantially planar second portion of thefirst mesh lies.

In some arrangements, the first mesh may be a flexible sheet formed inthe shape of a cone or a frustum of a cone.

In some arrangements, the first mesh may define a pocket. The pocket ofthe first mesh may be stamped to form a cavity in the pocket. In somesuch arrangements, when the first mesh is stamped by a tool, a bottomsurface of the cavity of the first mesh may conform to a bottom surfaceof the tool. When the first mesh is stamped by a tool having protrusionsextending from a flat base, a bottom surface of the first mesh may havecorresponding protrusions extending from the bottom surface upon beingstamped by the tool.

In some arrangements, when scanning each of the successive layers of thematerial at predetermined locations, a third series of segmentsextending in a third direction and a fourth series of segments extendingin a fourth direction transverse to the third direction may be formed.In some such arrangements, each of the segments of the third series ofsegments may overlap a plurality of segments of the fourth series ofsegments and may underlap a plurality of segments of the fourth seriesof segments. In this manner, the third and fourth series of segments mayform a second mesh. In some such arrangements, when scanning each of thesuccessive layers at predetermined locations, at least one segment maybe formed that underlaps and overlaps at least one segment of the firstand second series of segments and at least one segment of the third andfourth segments such that the first and second meshes may be rotatablyattached to each other.

In some arrangements, the first and the third directions are the same.In the same or in other arrangements, the second and the fourthdirections are the same.

In some arrangements, any of the first and the second meshes may have aprofile substantially in the form of any of a square, a rectangle, acircle, and a triangle.

In some arrangements, the first and the second meshes may have edgesadjacent and substantially parallel to each other such that uponrotation of either of the edges about the other edge, the edges do notinterfere with such rotation.

In some arrangements, pluralities of the segments of the first andsecond series of segments may define a bore through a thickness of thescanned successive layers of the material.

In some arrangements, when scanning each of the successive layers atpredetermined locations an outer ring, and wherein ends of pluralitiesof the segments of the first and second series of segments are fused toan outer perimeter of the outer ring, an inner perimeter opposite theouter perimeter of the outer ring defining the bore through thethickness of the scanned successive layers of the material.

In some arrangements, when scanning each of the successive layers atpredetermined locations, an inner ring concentric with the outer ringmay be formed. In some such arrangements when scanning each of thesuccessive layers at predetermined locations, segments fused to andbetween the inner perimeter of the outer ring and an outer perimeteropposite an inner perimeter of the inner ring may be formed. In sucharrangements, the inner perimeter of the inner ring may define the borethrough the thickness of the scanned successive layers of the material.

In some arrangements, when scanning each of the successive layers atpredetermined locations a stud or rivet may be formed. In some sucharrangements, ends of pluralities of the segments of the first andsecond series of segments may fused to the perimeter of the stud orrivet.

In some arrangements, when scanning each of the successive layers atpredetermined locations, a third series of segments extending in a thirddirection and a fourth series of segments extending in a fourthdirection transverse to the third direction may be formed. In some sucharrangements, each of the segments of the third series of segments mayoverlap a plurality of segments of the fourth series of segments and mayunderlap a plurality of segments of the fourth series of segments. Inthis manner, the third and fourth series of segments may form a secondmesh. In some such arrangements, when scanning each of the successivelayers at predetermined locations, a solid section may be formed. Thesolid section may be fused to each of the first and second meshes. Inthis manner, the solid section may be movable relative to portions ofeach of the first and second meshes.

In some arrangements, when scanning each of the successive layers atpredetermined locations a hook extending from the first segment may beformed.

In some arrangements, the first segment may be fused to at least one ofthe second and the third segments.

In some arrangements, the first segment may be fused to only one of thesecond and the third segments.

In accordance with another aspect, bone ingrowth may be facilitated. Infacilitating such bone ingrowth, a porous tissue ingrowth structure maybe formed in the shape of a mesh implant. In forming the mesh implant, afirst layer of a material may be deposited onto a substrate. A firstlayer of the material may be scanned with a high energy beam to at leastpartially melt the first layer of the material. Successive layers of thematerial may be deposited onto the first layer. Each of the successivelayers of the material may be scanned with the high energy beam atpredetermined locations to form at least a first segment overlapping asecond segment and underlapping a third segment. The mesh implant may beshaped into a desired shape. The mesh implant may have a porosity topromote bone ingrowth. The mesh implant may be placed against a boneportion. A bone implant may be placed against bone cement such that thebone cement contacts both the mesh implant and the bone implant. Themesh implant may prevent contact of the bone cement with bone ingrowninto the mesh implant.

In accordance with another aspect, a three-dimensional structure may beformed. In forming the three-dimensional structure, a first layer of amaterial may be formed over at least a substrate. The first layer of thematerial may be scanned with a high energy beam to form a first pattern.The first pattern may include a first portion (a1) of a first solidportion (A). A second layer of the material may be deposited over thefirst layer of the material. The second layer of the material may bescanned with a high energy beam to form a second pattern. The secondpattern may include a first portion (b1) of a second solid portion (B).A third layer of the material may be deposited over at least asubstrate. The third layer of the material may be scanned with a highenergy beam to form a third pattern. The third pattern may include asecond portion (a2) of the first solid portion (A). A fourth layer ofthe material may be deposited over at least the second layer of thematerial. The fourth layer of the material may be scanned with a highenergy beam to form a fourth pattern. The fourth pattern may include athird portion (a3) of the first solid portion (A). A fifth layer of thematerial may be deposited over at least the third layer of the material.The fifth layer of the material may be scanned with a high energy beamto form a fifth pattern. The fifth pattern may include a first portion(c1) of a third solid portion (C). A sixth layer of the material may bedeposited over at least the fifth layer of the material. The sixth layerof the material may be scanned with a high energy beam to form a sixthpattern. The sixth pattern may include a fourth portion (a4) of thefirst solid portion (A). The first, second, third, and fourth portionsof the first solid portion (A) may be attached to each other such thatthe first solid portion (A) at least partially wraps around the secondsolid portion (B) and the third solid portion (C). An example of a modelused to form such a three-dimensional structure is shown in FIG. 4A inwhich examples of first, second, third, and fourth portions, and first,second, and third solid portions are labeled accordingly.

In some arrangements, at least some of the second, third, fourth, andfifth layers may be the same layer.

In some arrangements, the second solid portion (B) is the same as thethird solid portion (C) such that the first solid portion (A) forms alink.

In some arrangements, the first and third layers may be the same layersuch that the third pattern is part of the first pattern. In sucharrangements, the first pattern may further include a first portion (d1)and a second portion (d2) of a fourth solid portion (D). The firstportion (d1) and the second portion (d2) of the fourth solid portion (D)may be offset from the first portion (a1) and the second portion (a2) ofthe first solid portion (A) within the first pattern. In sucharrangements, the second and fifth layers may be the same layer suchthat the fifth pattern is part of the second pattern. In sucharrangements, the first portion (b1) of the second solid portion (B) andthe first portion (c1) of the third solid portion (C) may be offset fromeach other. In such arrangements, the fourth and sixth layers may be thesame layer such that the sixth pattern is part of the fourth pattern. Insuch arrangements, the fourth pattern may further include a thirdportion (d3) and a fourth portion (d4) of the fourth solid portion (D).In such arrangements, the third portion (d3) and the fourth portion (d4)of the fourth solid portion (D) may be offset from the third portion(a3) and the fourth portion (a4) of the first solid portion (A) withinthe fourth pattern. In such arrangements, the first, second, third, andfourth portions of the fourth solid portion (D) may be attached to eachother such that the fourth solid portion (A) weaves around the secondsolid portion (B) and the third solid portion (C) in the opposite mannerthat the first solid portion weaves around the second solid portion (B)and the third solid portion (C).

In some arrangements, at least one of the second portion (a2) and thethird portion (a3) of the first solid portion (A) may be fused to atleast one of the first portion (b1) of the second solid portion (B) andthe first portion (c1) of the third solid portion (C).

In accordance with another aspect, a non-transitory computer-readablestorage medium may have computer readable instructions of a programstored on the medium. The instructions, when executed by a processor,cause the processor to perform a process of preparing acomputer-generated model of a three-dimensional structure constructed ofunit cells. In performing the process, a computer-generated componentfile may be prepared. The computer-generated component file may includea porous CAD volume which may have a boundary. A space may be populated,by a processor, to include the porous CAD volume. The porous CAD volumemay be populated with unit cells. Each of the unit cells may bepopulated, by a processor, with at least one segment geometry to form aplurality of segment geometries. A first segment geometry of theplurality of segment geometries may overlap a second segment geometry ofthe plurality of segment geometries and underlap a third segmentgeometry of the plurality of segment geometries.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional diagram of a system in accordance with anembodiment;

FIGS. 2-4B are various views of three-dimensional model representationsof unit cells having wireframes located therein in accordance with otherembodiments;

FIG. 5 is a process flow diagram in accordance with another embodiment;

FIG. 6 is an example of a mesh sheet in accordance with anotherembodiment;

FIGS. 7A-7D are illustrative profile views of mesh sheets in accordancewith another embodiment;

FIG. 8 is an example of an application of the mesh sheet of FIG. 6;

FIGS. 9A and 9B are perspective views of a three-dimensional modelrepresentation of portions of a mesh sheet in accordance with anembodiment;

FIG. 9C is a perspective view of a three-dimensional modelrepresentation of a unit cell for use in preparing the three-dimensionalmodel representation of the portions of the mesh sheet shown in FIGS. 9Aand 9B;

FIGS. 10A-12C are views of applications of mesh sheets in accordancewith embodiments;

FIG. 13A is a perspective view of a three-dimensional modelrepresentation of a portion of a mesh sheet in accordance with anembodiment;

FIG. 13B is an example of an application of the mesh sheet of FIG. 13A;

FIGS. 14A-15 are perspective views of three-dimensional modelrepresentations of a portion of mesh sheets in accordance with anembodiment;

FIG. 16 is an example of a mesh sheet in accordance with an embodiment;

FIGS. 17A-17C are examples of applications of mesh sheets in accordancewith embodiments;

FIGS. 18A-18C are views of an application of mesh sheets in accordancewith embodiment;

FIGS. 19A and 19B are perspective and side views of a mesh sheet inaccordance with an embodiment;

FIG. 19C is a perspective view of a tool for use with the mesh sheet ofFIGS. 19A and 19B in accordance with an embodiment;

FIGS. 19D and 19E are perspective and side views of the mesh sheet ofFIGS. 19A and 19B after deformation of the mesh sheet by the tool ofFIG. 19C in accordance with an embodiment;

FIG. 20A is a side view of a tool for use with the mesh sheet of FIGS.19A and 19B in accordance with an embodiment;

FIG. 20B is a side view of the mesh sheet of FIGS. 19A and 19B afterdeformation of the mesh sheet by the tool of FIG. 20A in accordance withan embodiment; and

FIG. 21 is a perspective view of an application of the deformed meshsheets of either of FIGS. 19D and 20B.

DETAILED DESCRIPTION

This invention relates generally to generating computer models ofthree-dimensional structures. These models may be used to prepare poroustissue in-growth structures in medical implants and prostheses. Themodels may include features corresponding to tangible structures.

FIG. 1 depicts system 105 that may be used, among other functions, togenerate, store and share three-dimensional models of structures. System105 may include at least one server computer 110, first client computer115, and in some instances, at least second client computer 130. Thesecomputers may send and receive information via network 140. For example,a first user may generate a model at first client device 115. The modelmay then be uploaded to server 110 and distributed via network 140 tosecond client computer 130 for viewing and modification by a seconduser, who or which may be the first user.

Network 140, and intervening communication points, may comprise variousconfigurations and protocols including the Internet, World Wide Web,intranets, virtual private networks, wide area networks, local networks,private networks using communication protocols proprietary to one ormore companies, Ethernet, WiFi and HTTP, and various combinations of theforegoing. Such communication may be facilitated by any device capableof transmitting data to and from other computers, such as modems (e.g.,dial-up, cable or fiber optic) and wireless interfaces. Although only afew devices are depicted in FIG. 1, a system may include a large numberof connected computers, with each different computer being at adifferent communication point of the network.

Each of computers 110, 115, and 130 may include a processor and memory.For example, server 110 may include memory 114 which stores informationaccessible by processor 112, computer 115 may include memory 124 whichstores information accessible by processor 122, and computer 130 mayinclude memory 134 which stores information accessible by processor 132.

Each of processors 112, 122, 132 may be any conventional processor, suchas commercially available CPUs. Alternatively, the processors may bededicated controllers such as an ASIC, FPGA, or other hardware-basedprocessor. Although shown in FIG. 1 as being within the same block, theprocessor and memory may actually comprise multiple processors andmemories that may or may not be stored within the same physical housing.For example, memories may be a hard drive or other storage media locatedin a server farm of a network data center. Accordingly, references to aprocessor, memory, or computer will be understood to include referencesto a collection of processors, memories, or computers that may or maynot operate in parallel.

The memories may include first part storing applications or instructions116, 126, 136 that may be executed by the respective processor.Instructions 116, 126, 136 may be any set of instructions to be executeddirectly (such as machine code) or indirectly (such as scripts) by theprocessor. In that regard, the terms “applications,” “instructions,”“steps” and “programs” may be used interchangeably herein.

The memories may also include second part storing data 118, 128, 138that may be retrieved, stored or modified in accordance with therespective instructions. The memory may include any type capable ofstoring information accessible by the processor, such as a hard-drive,memory card, ROM, RAM, DVD, CD-ROM, write-capable, and read-onlymemories or various combinations of the foregoing, where applications116 and data 118 are stored on the same or different types of media.

In addition to a processor, memory and instructions, client computers115, 130, 131, 133 may have all of the components used in connectionwith a personal computer. For example, the client computers may includeelectronic display 150, 151 (e.g., a monitor having a screen, atouch-screen, a projector, a television, a computer printer or any otherelectrical device that is operable to display information), one or moreuser inputs 152, 153 (e.g., a mouse, keyboard, touch screen and/ormicrophone), speakers 154, 155, and all of the components used forconnecting these elements to one another.

Instructions 126, 136 of the first and second client devices 115, 130may include building applications 125, 135. For example, the buildingapplications may be used by a user to create three-dimensionalstructures, such as those described further herein. The buildingapplications may be associated with a graphical user interface fordisplaying on a client device in order to allow the user to utilize thefunctions of the building applications.

A building application may be a computer-aided design (CAD) 3-D modelingprogram or equivalent as known in the art. Available CAD programscapable of generating such a structure include Autodesk® AutoCAD®, Creo®by Parametric Technology Corporation (formerly Pro/Engineer), SiemensPLM Software NX™ (formerly Unigraphics NX), SOLIDWORKS® by SolidWorksCorporation, and CATIA® by Dassault Systemes. Such structures may bethose described in the '421 Application.

Data 118, 128, 138 need not be limited by any particular data structure.For example, the data may be stored in computer registers, in arelational database as a table having a plurality of different fieldsand records, or XML documents. The data may also be formatted into anycomputer-readable format such as, but not limited to, binary values,ASCII or Unicode. Moreover, the data may comprise any informationsufficient to identify the relevant information, such as numbers,descriptive text, proprietary codes, pointers, references to data storedin other memories (including other network locations) or informationthat is used by a function to calculate the relevant data. For example,data 128 of first client device 115 may include information used bybuilding application 125 to create three-dimensional models.

In addition to the operations described above and illustrated in thefigures, various other operations will now be described. It should beunderstood that the following operations do not have to be performed inthe precise order described below. Rather, various steps may be handledin a different order or simultaneously. Steps may also be omitted oradded unless otherwise stated herein.

An overall three-dimensional representation of a component may first begenerated by preparing a CAD model. This overall CAD model may becomprised of one or more distinct CAD volumes that are intended to bemanufactured as either solid or porous physical structures, i.e.,constructs.

Solid CAD volumes, which correspond to manufactured solid physicalstructures, can be sliced into layers of a predetermined thickness readyfor hatching, re-merging with the porous volume (post-latticegeneration), and subsequent manufacture.

Porous CAD volumes, such as porous CAD volume 100 shown in the exampleof FIG. 2 and which correspond to manufactured porous geometries, can beprocessed using bespoke software. As in the example of FIG. 2, a porousgeometry is made up of one or more segments 110, 120 organized withintessellated unit cells 105. Many designs are possible for a porousgeometry which allows the porous geometry to impart various strength,surface, and/or other characteristics into the porous CAD volume. Forexample, porous geometries can be used to control the shape, type,degree, density, and size of porosity within the structure. Such porousgeometry shapes can be dodecahedral, octahedral, tetrahedral (diamond),as well as other various shapes.

As further shown in FIG. 2, porous CAD volume 100 is formed by aplurality of unit cells 105 which each contain curvilinear segmentgeometry 110 and curvilinear segment geometry 120. Curvilinear segmentgeometry 110 within each unit cell 105 extend from an end 111 thereoflocated at a center of a lower left edge of the unit cell to an end 112thereof located at a center of an upper right edge of the unit cell, andcurvilinear segment geometries 120 within each unit cell 105 extend froman end 121 thereof located at a center of an upper left edge of the unitcell to an end 122 thereof located at a center of a lower right edge ofthe unit cell.

Unit cells 105 are adjacent to each other such that end 112 ofcurvilinear segment geometry 110 within one unit cell 105 abuts, andindeed is the same as, end 121 of curvilinear segment geometry 120within adjacent unit cell 105 and such that end 122 of curvilinearsegment geometry 120 within one unit cell 105 abuts, and is the same as,end 111 of curvilinear segment geometry 110 within adjacent unit cell105. As shown, curvilinear segment geometry 110 within each unit cell105 curves around curvilinear segment geometry 120 within the same unitcell. In this manner, a connected pair of curvilinear segment geometry110 and curvilinear segment geometry 120 within adjacent unit cells 105overlaps the other connected pair of curvilinear segment geometry 110and curvilinear segment geometry 120 within the same adjacent unitcells.

As shown in FIG. 3, porous CAD volume 100A includes unit cells 105formed adjacent to other unit cells 105 such that ends of curvilinearsegment geometries 110, 120 of one unit cell abut an end of the othercurvilinear segment geometry of respective curvilinear segmentgeometries 110, 120 of the adjacent unit cell. As further shown, aplurality of barb geometries 135 extend from various ends 111, 112 ofcurvilinear segment geometries 110 and ends 121, 122 of curvilinearsegment geometries 120 such that barb geometries 135 extend transverselyacross the curvilinear segment geometries 110, 120 corresponding to therespective ends. In this manner, a plurality of unit cells 105 may betessellated to form the porous CAD volume 100A.

When used for medical implants, barb geometries, such as barb geometries135, may correspond to physical barbs that encourage directionalfixation of the implants. In such applications, the barbs may vary inspacing and length. Such barbs may be but are not limited to being onthe order of 0.6-1.2 mm in length. Any directional barb hairs, branches,rods, and beads may also be incorporated into a porous mesh structure toencourage directional fixation with bone. As barb geometries, such asbarb geometries 135, may be placed at any predetermined or, conversely,at randomly selected positions along segment geometries of a porous CADvolume, barbs corresponding to the barb geometries may be placed at anysuch corresponding positions on segments corresponding to segmentgeometries.

Referring now to FIG. 4A, porous CAD volume 200A formed by tessellationof a plurality of unit cells 205A, 206A each containing linear segmentgeometry 210A and curvilinear segment geometry 220A. As in this example,opposing ends 211A, 212A of linear segment geometry 210A within eachunit cell 205A, 206A may extend from centers of opposite faces of theunit cell, and curvilinear segment geometry 220A of each unit cell 205Amay extend from an end 221A thereof located at a center of an upperfront edge of the unit cell, around the linear segment geometry, and toan end 222A thereof located at a center of an upper rear edge of theunit cell. In this manner, segment geometries 210A, 220A form portionsof mesh geometry.

A plurality of unit cells 205A and separately a plurality of unit cells206A may be adjacent to each other such that end 221A of curvilinearsegment geometry 210A of one unit cell 205A, 206A abuts end 222A ofcurvilinear segment geometry 220A of respective adjacent unit cell 205A,206A. As further shown, the plurality of unit cells 206A may be invertedrelative to the plurality of unit cells 205A, and end 211A of linearsegment geometry 210A of one unit cell 205A may abut end 212A of linearsegment geometry 210A of respective adjacent unit cell 206A. In thismanner, curvilinear segment geometries 210A of each of the plurality ofunit cells 205A, 206A and the linear geometries 210A of each of theplurality of unit cells 205A, 206A may collectively form a woven meshgeometry. As in the example shown, the linear segment geometries 210A ofthe plurality of unit cells 205A, 206A may all be parallel to eachother.

Referring to FIG. 4B, porous CAD volume 200B is formed by tessellationof a plurality of unit cells 205B, 206B each containing curvilinearsegment geometry 210B in which curvilinear segment geometry 210B of unitcell 206B is inverted relative to curvilinear segment geometry 210B ofunit cell 205B. As in this example, opposing ends 211B, 212B ofcurvilinear segment geometry 210B of each unit cell 205B, 206B mayextend from opposite corners of the respective unit cells. Unit cells205B may be diagonal from each other such that they share only onecommon edge, and similarly, unit cells 206B may be diagonal from eachother such that they share only one common edge. In this manner, ends212B of curvilinear segment geometries 210B of each of a first set ofunit cells 205B, 206B may abut ends 211B of curvilinear segmentgeometries 210B of each of a second set of unit cells 205B, 206B locateddiagonally to the first set of the unit cells. In this manner, aconnected pair of curvilinear segment geometry 210B of diagonallylocated set of unit cells 205B overlaps a connected pair of curvilinearsegment geometry 210B of diagonally located set of unit cells 206B toform mesh geometry. As shown, such mesh geometry may be in the form of awoven mesh.

A larger mesh geometry may be formed by adding further sets of the fourunit cells 205B, 206B to each of the four sets of two side faces 213,214 of adjoining unit cells 205B, 206B, i.e., to the side faces 213, 214around the circumference of the four-cubes shown in the illustration ofFIG. 4B. In alternative arrangements, the mesh geometry defined by thefour curvilinear segments 210B of the four unit cells 205B, 206B shownin FIG. 4B may be arranged in a single unit cell, which may betessellated to form a porous CAD volume.

Other variations of unit cells 105 and 205, 206 in which at least onesegment geometry defining the unit cell is curved or includes angledportions, which may be in the shape of a “V,” “W” or other combinationof linear portions, such that the segment geometry curves or wrapsaround another segment geometry of the unit cell are within the scope ofthe present technology. Such variations could also be used to formporous CAD volumes. In other arrangements, a CAD model may be generatedwithout forming unit cells and thus without tessellation of featureswithin the unit cells. Such CAD models created without tessellated unitcells may be in the form of a woven mesh, i.e., cross-hatch, geometrywith overlapping and underlapping strips, i.e., ribbons. In somealternative arrangements, woven mesh geometries may have a plurality ofadjacent segment geometries or set of segment geometries that overlapand underlap the same transverse corresponding segment geometries or setof segment geometries, e.g., in the form of a “double weave.” In othervariations of forming mesh geometries, the ends of the segment may be atany location within a unit cell so long as the segment geometries ofeach unit cell, alone or in combination with segment geometries ofadjacent unit cells overlap and underlap segment geometries within thesame unit cell or within adjacent unit cells, i.e., in a manner similarto the overlapping and underlapping of the segment geometries shown inFIGS. 4A and 4B. For example, ends may be but are not limited to beingat corners of unit cells, centers of edges of unit cells, and thecenters of faces of unit cells. In some arrangements, a percentage ofthe junctions where segment geometries of a porous CAD volume overlapeach other may be fused together.

When fusion of such junctions is unevenly distributed, anisotropy in aphysical mesh structure corresponding to a porous CAD volume may becreated.

Referring to FIG. 5, in an example of preparing a porous CAD volume ofsegment geometries, a computer-generated component file is prepared at ablock 191. The component file includes a porous CAD volume with aboundary having at least one predefined portion. At a block 192, a spacethat includes the porous CAD volume is populated, by a processor, withunit cells. Such a space may be defined by sets of coordinates, such asCartesian, polar, or spherical coordinates. At a block 193, the unitcells are populated with one or more segment geometries to form aplurality of segment geometries. As further shown at block 193, a firstcurvilinear segment geometry of the plurality of segment geometriesoverlaps a second segment geometry of the plurality of segmentgeometries and underlaps a third segment geometry of the plurality ofsegment geometries. In this manner, a computer-generated model of athree-dimensional structure constructed of segment geometries isprepared.

The above-described model geometries can be visualized in a number ofways, including but not limited to by voxelating the sliced output filesfrom bespoke software that is being applied in an additive layermanufacturing machine. Utilizing developed algorithms and the outputfiles, the data may be fed into a commercial software package, e.g.,MATLAB® by MathWorks, Inc., and the images produced can be interpreted.At an optional block 194, a tangible three-dimensional structure havinga shape corresponding to the computer-generated model may be produced.The shape of the three-dimensional structure may be in the form of amesh structure, such as a mesh implant.

The approaches for generating the three-dimensional models describedherein may be used for building various tangible structures andsurfaces, specifically structures and surfaces for medical implants.Upon completion of a CAD model including the porous geometries and anysolid geometries that may be connected to the porous geometries, anintended physical structure may be formed directly onto a substrateusing a layered additive manufacturing process, including but notlimited to electron beam melting (EBM), selective laser sintering (SLS),selective laser melting (SLM), and blown powder fusion for use withmetal powders. Techniques such as but not limited to SLS,three-dimensional inkjet printing (3DP), stereolithography (SLA), andfused filament fabrication (FFF) may be used with polymer powders orstrands to produce plastic constructs. Cellular scaffolds may be formedusing bioplotters or 3DP. Although a brief summary follows, many detailsof a process of melting powdered metal are given in the '332 and '081Publications. In an example of constructing a tangible structure from amodel build geometry using metal powder, a layer of metal powder may bedeposited onto a substrate. The substrate may be a work platform, asolid base, or a core, with the base or core being provided to possiblybe an integral part of the finished product.

The metal powder may be but is not limited to being made from any oftitanium, a titanium alloy, stainless steel, magnesium, a magnesiumalloy, cobalt, a cobalt alloy including a cobalt chrome alloy, nickel, anickel alloy including a nickel titanium alloy, tantalum, and niobium.In some embodiments, individual layers of metal may be scanned using adirected high energy beam, such as a continuous or pulsed laser ore-beam system to selectively melt the powder, i.e., melt the powder inpredetermined locations. Each layer, or portion of a layer, is scannedto create a plurality of predetermined porous or mesh physicalconstructs, and when necessary predetermined solid constructs, by pointexposure to the energized beam. This leads to the production of linear,curvilinear, or other shaped struts that correspond to the segmentsdescribed previously herein and eventually to a porous or mesh physicalconstruct, as will be described below. Successive layers are depositedonto previous layers and also are scanned. The scanning and depositingof successive layers continues the building process of the predeterminedporous geometries. As disclosed herein, continuing the building processrefers not only to a continuation of a porous or mesh physical constructfrom a previous layer but also a beginning of a new porous or meshphysical construct as well as the completion of the current porous ormesh physical construct.

In alternative arrangements, non-metallic materials may be used in suchadditive layer manufacturing processes. These materials may includeimplantable plastics including but not limited to wax, polyethylene (PE)and variations thereof, polyetheretherketone (PEEK), polyetherketone(PEK), acrylonitrile butadiene styrene (ABS), silicone, and cross-linkedpolymers; bioabsorbable glass, ceramics, and biological active materialssuch as collagen/cell matrices. Composites of any of these materials orthe metals described previously herein may be made as a combination withany of bone cement, bone, soft tissue, and cellular matrices and tissuecells.

A component structure or sub-structure thereof produced by theapproaches herein may be porous and if desired, the pores can beinterconnecting to provide an interconnected porosity. In someembodiments, the amount and location of porosity may be predetermined,and preferably lie in the range 50% to 90% as being suitable when usedas a bone ingrowth surface, and 20% to 90% as being suitable for polymerinterlock surfaces. This also applies to cases where the outer poroussection of a medical device is connected to host bone with bone cementor bone type adhesives for example.

When physical constructs are produced using a laser or electron beammelting process, a prefabricated base or core may act as a substratebuilding physical constructs. Such bases may be made of any of thematerials described previously herein for us in the additive layermanufacturing processes. In some instances, such materials may bedifferent than the materials for the successive layers built during theadditive layer manufacturing processes. Thus, a mixture of desired mixedmaterials can be employed. By way of example, porous layers can be builtonto an existing article, which itself may be porous or solid, made fromany of cobalt chrome, titanium or alloy, stainless steel, tantalum orniobium In this example, the existing article may be an orthopaedicimplant. In such a manner, the approaches described herein may beexploited to produce commercially saleable implants with bone in-growthstructures having porous surfaces with a predetermined scaffoldstructure. The constructed medical implant, which may correspond to themesh geometries described previously herein, may have a porosity andarchitecture optimized, to create very favorable conditions so that bonein-growth takes place in a physiological environment and the overalloutcome favors long-term stability.

Because a laser or electron beam melting process may not requiresubsequent heat treatment or the temperature at which this heattreatment occurs is lower than any critical phase change in thematerial, the initial mechanical properties of any base metal to which aporous structure is applied may be preserved.

The equipment used for additive layer manufacturing of implants could beone of many currently available, including but not limited to thosemanufactured by Renishaw, SLM Solutions, Realizer, EOS, Concept Laser,Arcam and the like. The laser or electron beam may also be acustom-produced laboratory device.

As shown in FIG. 6, mesh sheet 150 was produced by melting successivelayers of metal powder. To produce physical constructs of this form,with reference to FIG. 3, spots corresponding to ends 111 of curvilinearsegments 110 and ends 122 of curvilinear segments 120 may be formedduring production of one layer of an intended physical structurecorresponding to porous CAD volume 100A, spots corresponding to ends 121of curvilinear segments 120 and ends 112 of curvilinear segments 110 maybe formed using a high energy beam during production of another layer ofthe intended physical structure corresponding to porous CAD volume 100A,and spots corresponding to portions of curvilinear segments 110 andportions of curvilinear segments 120 may be formed during production ofother layers of the intended physical structure corresponding to porousCAD volume 100A. Such spots may be formed using an SLS or SLM process inwhich when a laser is the high energy beam, the powder particles mayhave a diameter on the order of between and including 5 and 50 μm, andwhen an electron beam is the high energy beam, the powder particles mayhave a diameter on the order of between and including 75 and 150 μm. Ina similar manner, the geometries of the porous CAD volumes 100, 200A,and 200B as described previously herein may be formed into mesh sheets.Similar constructions may be but are not limited to being formed usingany of the other additive manufacturing processes discussed previouslyherein, including 3DP, SLA, FFF, and digital light processing (DLP).

Again referring to FIG. 6, mesh sheet 150 is made of titanium. Due tothe rigidity of the material, mesh sheet 150 has been trimmed to size bya pair of scissors, producing little debris relative to other devicesthat require modification from a Midas Rex, such as with cone and sleeveaugments. Mesh sheet 150 is malleable due to its minimal thickness andthus has been curled into shape. As shown, mesh sheet 150 has also beencoated with a PERI-APATITE® hydroxyapatite coating but remains porous topromote bone in-growth. Although the surfaces of mesh sheet 150 arerelatively rough, in alternative arrangements, at least one surface ofthe mesh sheet may be smooth to prevent irritation to surrounding softtissues. Such surface may be produced using the techniques taught inU.S. Patent Application Publication No. 2013/0268085, now U.S. Pat. No.9,180,010 (“the '010 Patent”), incorporated by reference in its entiretyherein.

Referring to the illustrations of FIGS. 7A-7D, the CAD modeling andlayered additive manufacturing process in accordance with the presenttechnology can be used to form physical structures having a plurality ofmesh sheets 350A, 350B, 350C, 350D connected together by one or morelinks 355. The mesh sheets may be but are not limited to being formed ofsegments corresponding to segment geometries of porous CAD volumes, suchas but not limited to any of porous CAD volumes 100, 100A, 200A, and200B or may be formed of a series of overlapping and underlapping stripsprepared using a CAD model without the use of repeating unit cells, asdescribed previously herein. During preparation of any such woven meshpatterns, the overlapping and underlapping segments or strips may befused together at selected intersections or “cross-over” areas of thestrips to impart more rigidity to the mesh at the fused areas.

In such arrangements, the physical mesh sheet constructs may have butare not limited to having a square profile such as in FIG. 7A, arectangular profile such as in FIG. 7B, a circular profile such as inFIG. 7C, and a triangular profile such as in FIG. 7D. Links 355, whichmay correspond to link geometries created within a CAD model, may haveclosed perimeters as shown, or may have open perimeters. Links 355 mayhave profiles which may be but are not limited to being circular,triangular, hexagonal, and octagonal. As in the examples of FIGS. 7A-7D,links 355 may extend through openings defined by adjacent segments orstrips along edges of physical mesh sheet constructs, such as meshsheets 350A-D.

When forming such physical structures using any layered additivemanufacturing process, a predetermined thickness of mesh sheets 350A,350B, 350C, 350D and of links 355, corresponding to a slice height of aCAD model inputted into a layered additive manufacturing device, may begenerated during production of a single layer of an intended physicalstructure. In this manner, a portion of each of mesh sheets 350A-D andof each of links 355 shown in FIGS. 6A-6D may be produced duringformation of a single layer of the physical structures shown in FIGS.7A-7D.

There are a number of useful applications for the mesh sheets. As shownin FIG. 8, mesh sheet 150 is in the form of a foil such that the meshsheet may be press fit into a bony void space, such as that shown inbone 1. As shown, mesh sheet 150 has a coated outer surface thatpromotes mechanically strong bone in-growth and also has a coated innersurface that provides a textured surface to rigidly fix bone cement,when such cement is applied to the inner surface, in the shape of theinner surface of the mesh sheet. For this type of application, meshsheet 150 has a maximum allowable pore size to prevent seepage of thecement through the mesh sheet causing undesirable bone-to-cementcontact. Below a specific pore size, bone cement is at its “doughphase,” a phase in which the cement is viscous enough not to stick to asurgeon's glove, does not penetrate through the mesh. Randomizing theunit cell structures within a porous CAD volume may also limit the flowof bone cement.

As shown in FIGS. 9A and 9B, a CAD model of mesh sheet geometry 450includes a set of connected link geometries 455A oriented in a verticaldirection and link geometries 455B oriented in a horizontal direction. A“chain link” mesh sheet corresponding to this CAD model including a setof connected links may be formed using any of the additive layermanufacturing processes described previously herein in accordance withthe present technology.

Referring again to FIGS. 9A and 9B, as shown, each link geometry 455A,455B is a substantially planar open hexagon formed of six connectedsegments 410 which are connected to a plurality of other link geometries455A, 455B. Each link geometry 455A, 455B has a closed perimeter suchthat a physically produced link corresponding to this link geometry maynot be separated from other links to which the physically produced linkis connected without severing one of the connected links. In alternativearrangements, at least some physically produced links may have anopening through their perimeters such that links to which a link isconnected may be removed through the opening. In instances in which theopening of an open perimeter is too small, a link having such an openingmay be deformed to widen such opening.

In one arrangement of forming mesh sheet geometry 450, each linkgeometry within a CAD model may be modeled individually without the useof tessellated unit cells. In an alternative arrangement as shown in theexample of FIG. 9C, unit cell 405 may be tessellated to form mesh sheetgeometry 450. As shown, unit cell 405 includes one link geometry 455Ainterlocked with one link geometry 455B. With reference to FIGS. 9A and9B, upon tessellation of unit cell 405 to form a porous CAD volumecontaining mesh sheet geometry 450, each link geometry 455A of one unitcell becomes interlocked with link geometries 455B of adjacent unitcells, and each link geometry 455B of one unit cell becomes interlockedwith link geometries 455A of adjacent unit cells. In this manner, in theexample of FIGS. 9A and 9B, each link geometry 455A becomes interlockedwith four link geometries 455B and each link geometry 455B becomesinterlocked with four link geometries 455A.

In the example of FIGS. 9A and 9B, planes defined by a widest dimensionof interlocked link geometries 455A, 455B are arranged orthogonally toeach other. Interlocked link geometries 455A, 455B are spaced apart aslight distance from each other and have the same size. In alternativearrangements, interlocked link geometries may be set at any ofnon-orthogonal angles to each other, different spacings relative to eachother, and different sizes relative to each other. Through thesevariations, any of the porosity and flexibility of mesh sheetscorresponding to modeled mesh sheet geometries may be varied. In somealternative arrangements, unit cells, such as unit cells 405, may beoffset by a distance that is different than the spacing betweeninterlocked link geometries of each unit cell to form a non-uniform meshgeometry. In some alternative arrangements, some regions of a meshgeometry may be different in any dimension than other regions of a meshsheet geometry to form varying porosity, which may be a gradientporosity, within a mesh sheet corresponding to the mesh geometry.

When forming a physical structure corresponding to mesh sheet geometry450, which may be a mesh sheet or other flexible construct such as thoseshown in FIGS. 12A and 13B described further herein, a bottom portion oflinks, such as a bottom portion of a link corresponding to vertices 456of link geometries 455A, may be formed during preparation of a firstlayer of the physical structure of the mesh sheet geometry by anadditive layer manufacturing device. Successive layers of the physicalstructure may then be prepared by the additive layer manufacturingdevice to form complete links corresponding to link geometries 455A,455B in which links corresponding to link geometries 455A define planesthat are aligned vertically, i.e., orthogonally, with respect to asubstrate on which the physical structure is formed, and linkscorresponding to link geometries 455B define planes that are alignedhorizontally, i.e., parallel, with respect to the substrate. In thismanner, and with reference to FIGS. 9A-9C, during preparation of thesuccessive layers, only portions of links corresponding to width 457along opposite sides of the vertically-aligned hexagonal links 455A maybe formed in the layers forming links corresponding tohorizontally-aligned hexagonal links 455B.

The size of the segments forming the links, which correspond to thesegment geometries forming the link geometries, such as link geometries455A, 455B, the shape of any of the segments and the links, and thus thesizes of pores defined by the links may be adjusted to suit a particularapplication of a physical construct such as a mesh sheet. Such variablesmay be used to control flexibility, range of motion, and strength of anoverall construct, such as a mesh sheet as well as to control any of theamount of tissue ingrowth and the egress of contained materials, withpore size and shape optimized to pressurize doughy bone cements ormorselized bone graft materials. To achieve these goals, the pore sizespreferably should be greater than 300 μm and strut sizes preferablyshould be greater than 100 μm. In this manner and depending on materialchoice, the physical construct may have any of a relatively high tensilestrength, low flexion and compressive stiffness, variable tensilestiffness, variable stiffness, and ductility.

Link geometries, and thus their corresponding links in physicalconstructs, may be but are not limited to being in the shape of any of ahexagon, a circle, an ellipse, a square, a triangle, a rectangle, andany combination of these shapes. Links may be planar, such as linkscorresponding to link geometries 455A, 455B in the example of FIGS.9A-9C, as well as non-planar, in which links may extend in threedimensions, e.g., a kinked hex design. In some arrangements, the ratioof strut size to pore size for a given shape of strut corresponding to asegment in a CAD model may be varied to influence flexibility, range ofmotion, and strength in some or all directions. The ratio of linksconnected to each link may be adjusted throughout all or a portion of aflexible construct such as a mesh sheet. For example, in a preferredarrangement, a connected link ratio of 4:1 may be used to make a uniformsheet construct. In another example, a connected link ratio of 2:1 maybe used to make a chain construct, and in yet another example,odd-numbered connected link ratios may be used to create discontinuousflexible constructs.

Physical constructs formed using link geometries may have a gradedporosity by varying any of link size and shape within the same constructto provide for any of variable flexibility, variable range of motion,and variable strength throughout the construct. In some arrangements,physical constructs formed using the link geometries may be formed withanisotropy by varying any of link size and shape, by varying strut sizeand shape, or by selectively fusing some links to each other. Links maybe coated with various biocompatible substances, such as but not limitedto hydroxyapatite, to facilitate biological bone ingrowth. Links mayalso coated to minimize wear and also with antibiotic eluting coating inorder to treat infection.

Following formation of a flexible construct such as chain link meshconstructs, mechanical and flexural properties may be adjusted byvarious post-processing techniques. In one arrangement, the flexibleconstruct may be rolled into a cylinder, increasing the yield strengthof the construct along the axis of the cylinder. In another arrangement,one flexible construct may be stacked onto or nested within anotherflexible construct such that the stacked or nested constructs interactto constrain or augment each other. In some applications, the flexibleconstruct may be shaped, such as by rolling or flattening, such that theconstruct does not transmit compressive loads.

As shown in FIGS. 10A-10C, in one application of the chain link meshsheets, mesh sheet 450A, which has been formed using an additive layermanufacturing process based on a mesh sheet geometry substantiallysimilar to mesh sheet geometry 450, acts as a trochanteric gripper whichmay be placed over the trochanter of a femur to provide an ingrowthsurface Shell 440 is then placed over mesh sheet 450A and around thetrochanter. Cables 15, which as shown are cerclage wires, may be wrappedaround mesh sheet 450A to hold mesh 450A in place or, alternatively, maybe wrapped around shell 440, such as by being passed around or through athickness of spaced-apart arms of shell 440, to hold the assembly of theshell and mesh sheet 450A in place.

Referring now to FIGS. 11-17D, the chain link and mesh sheets may beproduced along with additional features by any of the additive layermanufacturing processes described previously herein. As shown in FIG.11, mesh sheet 550 includes a woven mesh pattern 551 and an alphanumericpattern 552 fused to the woven mesh pattern, in which the alphanumericpattern is formed substantially as shown and described in the '010Patent, using an additive layer manufacturing device. During preparationof mesh sheet 550, successive layers are added to basic mesh pattern 551to form alphanumeric pattern 552. In this manner, alphanumeric patternmay be used as product identifiers.

As shown in FIGS. 12A-12C, mesh sheets may include porous attachmentcomponents. In the example of FIG. 12A, mesh sheet 650A includes chainlink pattern 651A and a porous attachment component 652A fused to thechain link pattern at spaced-apart regions of the chain link pattern. Inthe example of FIGS. 12B and 12C, mesh sheet 650B includes woven meshpattern 651B and porous attachment component 652B. In these examples,porous attachment components 652A, 652B have been added to both sides ofwoven mesh pattern 651B during an additive layer manufacturing process.Porous attachment components may be lattice structures such as thosedisclosed in the '332 Publication as in the example shown, or may be inthe form of woven mesh or chain link patterns. In applications forfacilitating biological attachment of bone, porous attachmentcomponents, such as porous attachment components 652A, 652B, may be usedand may have a pore size in the range of approximately 100-1000 μm and aporosity which preferably may be at least 50%. Porous attachmentcomponents designed to function as scaffold cells for biologicalregeneration preferably may have a pore size greater than 100 μm and aporosity greater than 55%. In alternative arrangements (not shown),porous attachment components may be other types of porous structuresincluding but not limited to woven mesh or chain link mesh structures,which may have a pore size and porosity that is different than the mesh,chain link pattern, or other pattern, which may be porous or non-porous,to which the porous attachment components may be attached.

As shown in FIG. 12C, mesh sheet 650B, acting as a foil, may be rolledinto a cylindrical shape and placed or pressed into a bony void space,such as in the base of a tibia bone 1, as in this example. Although notshown, mesh sheet 650A could be placed into a bony void space in asimilar fashion. In such arrangements, bone cement then may be addedinside of the cylindrically-shaped mesh sheets 650A, 650B. In thismanner, mesh sheets 650A, 650B may promote better mechanical rigiditybetween live bone and bone cement.

As shown in FIGS. 13A and 13B, eyelet 760 may be integrated into themesh sheets, chain link mesh sheet 750 in this example, during anadditive layer manufacturing process. Eyelet 760 may be modeled as solideyelet geometry 760A as shown in FIG. 13A having inner perimeter 761A,which may act as a through bore. Depending on the parameter settings ofthe additive layer manufacturing device, eyelet 760 may be substantiallysolid or somewhat porous through its thickness, upon production of thephysical structure of the eyelet, as shown in FIG. 13B. Mesh sheet 750was built in its entirety in layers using an additive layermanufacturing process. As shown, some of hexagonal links 755 of meshsheet 750 abut outer perimeter 762 of eyelet 760. Some of such links 755have open perimeters in which ends of the open perimeters of the linksare fused to eyelet 760. Eyelet 760 may be but is not limited to beingused for screw, wire, or cable attachment of mesh sheet 750 to otherobjects, such as bone or other tissue.

Referring to FIG. 14A, a CAD model includes mesh sheet geometry 850including stud geometry 860, which as shown may be a rivet, which may beused to prepare a corresponding mesh sheet with a corresponding stud.The stud corresponding to stud geometry 860 may be formed in the samemanner as eyelet 760 and thus may be substantially solid or somewhatporous through its thickness and may be fused to links, with theexception that the stud may include a spike, corresponding to spikegeometry 863, and may not include any type of through bore. Such studsmay allow the construct to be press fit to itself or other materials,including bone. In some alternative arrangements (not shown), a studgeometry may include a through hole.

In FIG. 14B, a mesh sheet geometry 850A generated in a CAD modelincludes a plurality of stud geometries 860A extending outwardly near anedge of the mesh sheet geometry which may be used to prepare acorresponding mesh sheet with a corresponding stud. As shown in FIG.14C, each stud geometry 860A includes a lower base geometry 861A, anupper base geometry 862A, and an intermediate section geometry 863Abetween the lower and upper bases. The stud corresponding to each studgeometry 860A may be fused to the rest of the mesh sheet correspondingto mesh sheet geometry 850A at a lower base corresponding to lower basegeometry 861A. Referring again to FIG. 14B, studs corresponding to studgeometries 860A may be formed, such as by an additive layermanufacturing process as described previously herein, on opposing endsof a mesh sheet corresponding to mesh sheet geometry 850A such that acable may be wrapped around an intermediate section of a studcorresponding to stud geometry 860A. In this manner, such a mesh sheetmay be tensioned to form a rolled construct, which in some arrangementsmay be used to enclose other materials, such as but not limited to bonegraft material.

Referring to FIG. 15, a hook may be added to the perimeter of a link asdemonstrated by hook geometry 965 attached at a vertex of hexagonal linkgeometry 955 at an outer perimeter of mesh sheet geometry 950. As shown,hook geometry 965 is in the form of a hexagonal link geometry having anopening at its perimeter. When prepared as a physical structure, themesh sheet corresponding to mesh sheet geometry 950 may be attached bythe hook corresponding to hook geometry 865 to other materials,including but not limited to biological and manufactured materials, ormay be attached to another portion of mesh sheet itself to form a wrapor covering.

As shown in FIG. 16, mesh sheet 1050 includes a plurality of porousattachment components 1052 and eyelets 1060 fused to chain link meshpattern 1051. Other combinations of features including but not limitedto woven mesh patterns, chain link mesh patterns, porous attachmentcomponents, and eyelets may be combined into single mesh sheets inaccordance with the present technology. In some arrangements, mesh sheet1050 may be used in applications designed to facilitate biologicalattachment of soft tissue, including muscles, tendons, and ligaments. Insuch arrangements, the porous attachment components preferably may havea pore size greater than 100 μm and a porosity greater than 55%. Usingcomponents designed to facilitate attachment of a construct, such as thecomponents described with respect to FIGS. 13A-16, the flexibleconstructs such as the mesh sheets described herein may be folded andattached to other media or to themselves to form a cavity that can beexpanded with a flowing material such as but not limited to bone cementor a combination of bone cement and another device, such as but notlimited to a hip or knee replacement, to fill a free-form bone defect.

Referring now to FIGS. 17A-17C, chain link mesh sheets provide a networkof links that form structures that are both porous and highly flexible.As in the example of FIG. 17A, mesh sheet 1150A may be folded to fill abony void cavity. As in the examples of FIGS. 17B and 17C, mesh sheets1150B and 1150C are positioned such that a middle portion of the sheetis substantially flat and an outer portion of the sheet is draped orextended around another object. Components employing the mesh sheet orflexible constructions described previously herein may be completelymanufactured in situ or may be partially manufactured for lateradjustment in the field to tailor the construct as needed. In someexamples, their flexible construction allows the mesh sheets to befolded to contain another material such as bone cement or morselizedbone graft where the composite structure of the mesh sheet and thecontained material exhibits modified mechanical properties, e.g.,enhanced rigidity when bone cement is added.

Referring now to FIGS. 18A and 18B, integrated mesh sheet 1250, which asshown may be termed a “strut graft,” was produced using an additivelayer manufacturing process such as those described previously herein.Mesh sheet 1250 includes spaced-apart first porous regions 1270 along anentire length of the mesh sheet, spaced-apart second porous regions 1275across an entire width of the mesh sheet except at the locations of thefirst porous region 1270, and third porous regions 1280 in all othersections of the mesh sheet. In the example shown, each of porous regions1270 and 1275 is in the form of chain link mesh patterns, as describedpreviously herein, and has a different porosity and pore size than theother regions. As in the example shown, third porous regions 1280 mayhave a relatively low porosity such that the third porous regions aresubstantially rigid. First porous regions 1270 may have the highestporosity among the porous regions 1270, 1275, 1280 such that the firstporous regions 1270 of mesh sheet 1250 are the most flexible of theporous regions. In this manner, as shown in FIG. 18B, mesh sheet 1250may be bent about first porous regions 1270 such that the mesh sheet maybe wrapped around bone 10 to aid in bone repair. Second porous regions1275 may have a higher porosity than third porous regions 1280 but alower porosity than first porous regions 1270 allowing for third porousregions 1280 to be bent about second porous regions 1275 as well as forcompression of mesh sheet 1250 along the second porous regions such thatthe second porous regions may provide a groove within the mesh sheetwhen compressed. In this manner, with reference to the radiograph ofFIG. 18C, cables 15, which as shown are cerclage wires, may be wrappedaround second porous regions 1275 of mesh sheet 250 such that the secondporous regions are compressed to hold the mesh sheet tightly against thebone and to form a groove to hold the longitudinal location of thecables.

In some alternative arrangements of mesh sheet 1250, holes, which may bethreaded, may be provided within third porous regions 1280. In thismanner, fasteners may be inserted into third porous regions 1280 tofacilitate attachment of mesh sheet 1250 to large bone fragments. Insome alternative arrangements of mesh sheet 1250, any of the first,second, and third porous regions may be in the form of other porouspatterns, such as lattice structures disclosed in any of the '332Publication, the '081 Publication, the '703 Patent, the '374 Patent, andthe '010 Patent.

Referring now to FIGS. 19A-19E, mesh sheet 1350 is substantially in theform of a woven mesh sheet pattern similar to the patterns describedpreviously herein, which may be produced using additive layermanufacturing techniques such as those also described previously herein.As shown in FIGS. 19A and 19B, mesh sheet 1350 includes rounded centralpocket 1358 extending from flat region 1359 of the mesh sheet. As shownin FIG. 19C, stamp 1385, which as shown is a tibial base stamp, includeshandle 1386 and semicylindrical base 1387 having bottom surface 1388that is substantially flat. With reference to FIGS. 19D and 19E, stamp1385 may be pressed into mesh sheet 1350 to form a cavity in the meshsheet. Due to the flexibility of mesh sheet 1350, central pocket 1358may be stretched such that the mesh sheet has substantially the sameform as semicylindrical base 1387 of stamp 1385.

As shown in FIGS. 20A and 20B, in an alternative arrangement, stamp 1485having protrusions 1489 extending from substantially flat bottom surface1488 of the stamp may used to press out central pocket 1358 of meshsheet 1350. In this manner, corresponding protrusions 1490 may be formedon a bottom of central pocket 1358.

As shown in FIG. 21, in one application, stamped mesh sheet 1350 may beplaced into a burred out cavity of a bone, such as a tibia 2 as shown,and adhered to the cavity. In this manner, mesh sheet 1350 provides asurface for bone ingrowth to strengthen the mechanical engagement of thebone and bone cement applied into the stamped central pocket 1358 of themesh sheet and thus aids in preventing subsidence of an onlay or inlayimplant placed onto the bone cement and mesh sheet combination withinthe bone cavity.

There are still other useful applications of the mesh sheet flexibleconstructs.

It is to be understood that the disclosure set forth herein includes allpossible combinations of the particular features set forth above,whether specifically disclosed herein or not. For example, where aparticular feature is disclosed in the context of a particular aspect,arrangement, configuration, or embodiment, that feature can also beused, to the extent possible, in combination with and/or in the contextof other particular aspects, arrangements, configurations, andembodiments of the invention, and in the invention generally.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1-33. (canceled)
 34. A porous tissue ingrowth implant comprising: afirst mesh sheet; a second mesh sheet; and a first plurality of links,each of the links of the first plurality of links being attached to thefirst mesh sheet and to the second mesh sheet without being attached toany other object.
 35. The implant of claim 34, wherein either one orboth of the first and the second mesh sheets include chain mail.
 36. Theimplant of claim 34, wherein either one or both of the first and thesecond mesh sheets are in the form of a woven mesh.
 37. The implant ofclaim 34, wherein at least the first mesh sheet has a rectangularprofile, a triangular profile, a hexagonal profile, or a circularprofile.
 38. The implant of claim 34, wherein each of the links of thefirst plurality of links forms a closed loop.
 39. The implant of claim34, wherein the first mesh sheet, the second mesh sheet, and the firstplurality of links are metallic.
 40. The implant of claim 34, furthercomprising: a third mesh sheet; and a second plurality of links, each ofthe links of the second plurality of links being attached to the secondmesh sheet and to the third mesh sheet without being attached to anyother object.
 41. The implant of claim 40, wherein each of the links ofthe second plurality of links extends in a first direction and each ofthe links of the first plurality of links extends in a second directiontransverse to the first direction.
 42. The implant of claim 40, whereineach of the links of both the first plurality of links and the secondplurality of links extends in the same direction.
 43. The implant ofclaim 40, further comprising: a fourth mesh sheet; a third plurality oflinks, each of the links of the third plurality of links being attachedto the third mesh sheet and to the fourth mesh sheet without beingattached to any other object; and a fourth plurality of links, each ofthe links of the fourth plurality of links being attached to the fourthmesh sheet and to the first mesh sheet without being attached to anyother object.
 44. The implant of claim 43, further comprising a fifthplurality of links, each of the links of the fifth plurality of linksbeing attached to the first mesh sheet and to the third mesh sheetwithout being attached to any other object.
 45. The implant of claim 43,wherein the first mesh sheet includes a first edge and a second edge,the second mesh sheet includes a third edge confronting and parallel tothe second edge and further includes a fourth edge, the third mesh sheetincludes a fifth edge confronting and parallel to the fourth edge andfurther includes a sixth edge, and the fourth mesh sheet includes aseventh edge confronting and parallel to the sixth edge and furtherincludes an eighth edge confronting and parallel to the first edge. 46.The implant of claim 40, further comprising a third plurality of links,each of the links of the third plurality of links being attached to thethird mesh sheet and to the first mesh sheet without being attached toany other object.
 47. The implant of claim 40, wherein the first meshsheet defines a first edge, the second mesh sheet defines a second edgeand a third edge, and the third mesh sheet defines a fourth edge,wherein the first edge confronts and is parallel to the second edge, andwherein the third edge confronts and is parallel to the fourth edge. 48.The implant of claim 47, further comprising fourth and fifth meshsheets, wherein each of the first and the fourth edges confront and areparallel to respective edges of the fourth and the fifth mesh sheets.49. The implant of claim 40, wherein each of the first mesh sheet, thesecond mesh sheet, and the third mesh sheet define respective verticespointing towards a common center.
 50. A porous tissue ingrowth implantcomprising: a first mesh section; a first plurality of links; a secondmesh section attached to the first mesh section via the first pluralityof links; a second plurality of links; and a third mesh section attachedto the second mesh section via the second plurality of links, whereineach of the first, the second, and the third mesh sections have adifferent porosity than porosities defined by each of the first and thesecond plurality of links, and wherein the second mesh section ismovable relative to the first mesh section about the first plurality oflinks and the second mesh section is movable relative to the third meshsection about the second plurality of links.
 51. The implant of claim50, wherein links of the first plurality of links are attached to thefirst mesh section and to the second mesh section without being attachedto any other object, and wherein links of the second plurality of linksare attached to the second mesh section and to the third mesh sectionwithout being attached to any other object.
 52. The implant of claim 50,wherein the first plurality of links and the second plurality of linksdefine different porosities.
 53. The implant of claim 50, furthercomprising: a third plurality of links; a fourth plurality of links; anda fourth mesh section attached to the third mesh section via the thirdplurality of links and attached to the first mesh section via the fourthplurality of links, wherein the fourth mesh section is movable relativeto the third mesh section about the third plurality of links and thefourth mesh section is movable relative to the first mesh section aboutthe fourth plurality of links, and wherein the first, second, third, andfourth mesh sections are substantially rigid.
 54. A porous tissueingrowth implant comprising: a first mesh sheet having a first pluralityof links; a second mesh sheet having a second plurality of links; and athird plurality of links, each of the links of the third plurality oflinks being attached to the first mesh sheet and to the second meshsheet and having either one or both of a different shape and a differentsize than the first and the second pluralities of links.
 55. The implantof claim 54, wherein the third plurality of links have a differentdiameter than the first plurality of links and the second plurality oflinks.